This invention concerns an adjusting drive for insert tighteners for fastening upper dies below the mounting table of a press ram.
U.S. Pat. No. 3,335,657 shows such an adjusting drive in which a spindle is mounted in the T-groove, which passes through a rotating but axially immovable threaded nut in a face plate jaw mechanically actuated by wedge surfaces, and is connected to a motor drive. More common than this are insert tighteners with hydraulically actuated face plate jaws, with these hydraulic insert tighteners not only hastening the tightening process and clamping the die more securely, but especially more accurately but with the spindle also being relieved of the tightening forces so that it can be of lighter design and is not subject to any wear that is caused by the stress of the high clamping forces. Adjusting drives are also known for insert tighteners in which the insert tightener is connected to drive elements by means of a roller thrust chain, with this roller thrust chain being supported by guide members in the T-groove so that it can transfer the compressive forces to push the insert tightener with the roller thrust chain into the tightening position and again pull it out of this position. Both spindle drives and roller thrust chain drives require either relatively large T-groove guides (weakening of the tie rod by the spindle bore) or a large structural space on the side of the press ram, so that the attachment of paneling becomes difficult and the space for moving handling equipment for transporting the workpiece is unnecessarily restricted.
On the other hand, the drive spindle or the roller thrust chain cannot be kept arbitrarily small, since they have to be of self-supporting design above the adjustment of path of the tightening element. Furthermore, known adjusting drives can only engage in the T-groove from one end, and have to have a cantilever design between the insert tightener and the bearing outside of the T-groove, because the smooth surfaces of the T-groove for guiding the tenon block must not be impaired.